Synthesis and characterization of new Schiff base bearing bis(pyrano[3,2-c]quinolinone): Efficient cationic dye adsorption from aqueous solution

Abstract

Organic compound water pollution is one of the difficult environmental issues facing the advancement of human civilization. So, New bis(pyrano[3,2-c]quinolinone) based on Schiff base adsorbent was prepared to participate in solving this problem. The synthesized adsorbent was characterized using FT-IR, 1H NMR, XRD, SEM, elemental analysis, N2- adsorption-desorption isotherm, SBET, and Pore size distribution studies. The obtained results revealed a significant improvement in the new schiff base surface texture and crystallinity. Further, pHzpc of the new adsorbent has been examined to be 3.7. Its decolorization efficiency toward methylene blue (MB) dye from an aqueous solution was examined. Also, the factors of pH, contact time, reaction temperature, and initial dye concentration were optimized. Overall, this study emphasized that the newly synthesized Schiff base act as an effective adsorbent (99%) at a very short time (5 min., 10 ppm dye concentration, pH = 9 and temperature = 25 °C) and can be regenerated for five cycles for the removal of MB dye from aqueous solutions. Freundlich isotherm model and pseudo-second order kinetic model were fit effectively for the MB dye adsorption experimental data. Also, the calculated thermodynamic parameters revealed a spontaneous and exothermic adsorption reaction. FT- IR study and computational chemistry study proved that the decolorization interaction mechanism between the positive (-N+) sites of MB dye and the negative (- OH) active sites of the new Schiff base adsorbent at the optimum conditions occurred as a physisorption process.